CN105305658A - Wireless electric energy transmission method, apparatus and system - Google Patents

Abstract

The invention discloses a wireless electric energy transmission method, apparatus and system. The method comprises the following steps: an emission apparatus transmitting energy corresponding to obtained AC power through an excitation coil in the emission apparatus to an emission coil in the emission apparatus; and the emission apparatus transmitting electric energy to a receiving apparatus through the emission coil, wherein the electric energy is generated by the emission coil according to the energy, the wire diameter of the emission coil is proportional to the cube of a result obtained by dividing a transmission distance by the wire diameter of the emission coil and is respectively proportional to the reciprocal of the square foot of vacuum magnetic permeability, first conductivity of the emission coil and first resonance angular frequency of the emission coil during work, and the transmission distance is the distance between the emission apparatus and the receiving apparatus. When the emission coil employs such a diameter, the whole electric energy transmission system can be at a critical coupling state, and the transmission efficiency can be obviously improved.

Description

Wireless power transmission method, device and system

Technical Field

The present invention relates to power transmission technologies, and in particular, to a wireless power transmission method, device, and system.

Background

Electric energy is an indispensable energy source in human life, the main transmission mode of the electric energy is realized through electric wires, and the position of the transmission mode is still irreplaceable until now. However, with the rapid development of science and technology, the traditional power supply mode also becomes unable to meet the actual demands of production and life, and the demand of modern people for wireless power transmission is more and more urgent.

Currently, magnetic coupling resonant wireless power transmission is an implementation mode of wireless power transmission. Specifically, the magnetic coupling resonant wireless power utilizes the resonance principle, so that high efficiency and high power can be obtained when the magnetic coupling resonant wireless power is transmitted at a medium distance (the transmission distance is generally several times of the diameter of a transmission coil), the power transmission is not influenced by a non-magnetic space obstacle, and the magnetic coupling resonant wireless power has the advantages of long transmission distance, small influence on an electromagnetic environment and high power.

However, in the wireless power transmission method of the prior art, the energy transmission efficiency of the wireless power transmission system is not always at the maximum value, and the energy transmission efficiency is low. Therefore, a wireless power transmission method is needed to improve the power transmission efficiency during wireless power transmission.

Disclosure of Invention

The invention aims to provide a wireless power transmission method, a wireless power transmission device and a wireless power transmission system, which are used for solving the problems that the energy transmission efficiency of the wireless power transmission method in the prior art is not always at the maximum value and is low.

In order to achieve the above object, an aspect of the present invention provides a wireless power transmission method, including:

the transmitting device transmits the energy corresponding to the acquired alternating current to a transmitting coil in the transmitting device through an exciting coil in the transmitting device;

the transmitting device transmits electric energy to the receiving device through the transmitting coil, and the electric energy is generated by the transmitting coil according to the energy;

the wire diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil, and is in direct proportion to the vacuum magnetic permeability, the first electric conductivity of the transmitting coil and the negative half power of the first resonance angular frequency of the work of the transmitting coil respectively; the distance between the transmitting device and the receiving device is a transmission distance.

Another aspect of the present invention further provides a wireless power transmission method, including:

the receiving device receives the electric energy transmitted by the transmitting device through a receiving coil of the receiving device;

the receiving device transmits the electric energy to a load coil in the receiving device through the receiving coil;

the wire diameter of the receiving coil is in direct proportion to the cube of the transmission distance divided by the radius of the receiving coil, and is in direct proportion to the vacuum magnetic permeability, the second electric conductivity of the receiving coil and the negative half power of the second resonance angular frequency of the work of the receiving coil respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

Yet another aspect of the present invention provides a wireless power transmission apparatus, including:

an excitation coil for transmitting energy corresponding to the acquired alternating current to a transmitting coil, and the transmitting coil for transmitting electric energy generated according to the energy to a wireless electric energy receiving device;

the wire diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil, and is in direct proportion to the vacuum magnetic permeability, the first electric conductivity of the transmitting coil and the negative half power of the first resonance angular frequency of the work of the transmitting coil respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

Still another aspect of the present invention provides a wireless power transmission apparatus, including:

the receiving coil is used for receiving the electric energy transmitted by the transmitting device, and the load coil is used for receiving the electric energy transmitted by the receiving coil;

wherein the wire diameter of the receiving coil is proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is proportional to the second vacuum permeability, the second electrical conductivity, and the negative half power of the second resonance angular frequency, respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

Another aspect of the present invention provides a wireless power transmission system, including: any wireless power transmitting device and any wireless power receiving device on the market, wherein the wire diameter of the transmitting coil is equal to that of the receiving coil, the first resonance angular frequency is equal to the second resonance angular frequency, the first conductivity is equal to the second conductivity, and the radius of the transmitting coil is equal to that of the receiving coil.

According to the technical scheme, under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius and the resonant working frequency of the receiving coil are fixed, if the line diameter of the receiving coil is in direct proportion to the cube of the transmission distance divided by the radius of the receiving coil and is in direct proportion to the vacuum magnetic permeability, the second electric conductivity and the negative half power of the second resonance angular frequency respectively, when the receiving device receives the electric energy transmitted by the transmitting device, the whole electric energy transmission system is in a critical coupling state, so that the transmission efficiency is obviously improved.

Drawings

Fig. 1 is a flowchart of a wireless power transmission method according to an embodiment of the present invention;

fig. 2 is a flowchart of a wireless power transmission method according to another embodiment of the present invention;

fig. 3 is an equivalent circuit diagram of a transmitting device and a receiving device according to an embodiment of the present invention;

fig. 4 is a flowchart of a wireless power transmission method according to another embodiment of the invention;

fig. 5 is a flowchart illustrating a wireless power transmission method according to still another embodiment of the invention;

fig. 6 is a circuit diagram of a wireless power transmitting apparatus according to another embodiment of the invention;

fig. 7 is a circuit diagram of a wireless power receiving device according to another embodiment of the invention.

Detailed Description

Example one

Fig. 1 is a flowchart of a wireless power transmission method according to an embodiment of the present invention, where an execution main body of the embodiment is a transmitting device, and as shown in fig. 1, the wireless power transmission method includes:

step 101, the transmitting device transmits energy corresponding to the acquired alternating current to a transmitting coil in the transmitting device through an exciting coil in the transmitting device, wherein the wire diameter of the transmitting coil is proportional to the transmission distance divided by the cube of the radius of the transmitting coil, and is respectively proportional to the vacuum magnetic permeability, the first electrical conductivity of the transmitting coil, and the negative half power of the first resonance angular frequency of the transmitting coil, and the distance between the transmitting device and the receiving device is the transmission distance.

The first conductivity is determined by the material of the transmitting coil, the transmitting coil may be a copper wire or an aluminum wire, the transmission distance and the radius of the transmitting coil may be selected according to actual needs, for example, the transmission distance may be selected to be 50 cm, and in order to limit the volume of the transmitting device, the radius of the transmitting coil may be selected to be 10 cm.

Step 102, the transmitting device transmits electrical energy to the receiving device via the transmitting coil, the electrical energy being generated by the transmitting coil as a function of the energy.

Specifically, the excitation coil is composed of an excitation source and a single-turn coil. The exciting coil and the transmitting coil transmit energy from the exciting coil to the transmitting coil through a direct coupling relationship. Wherein the transmitting coil of the transmitting device is to be placed coaxially with the receiving coil of the receiving device.

It can be seen that, under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius, and the resonant operating frequency of the transmitting coil are fixed, if the line diameter of the transmitting coil is directly proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is respectively directly proportional to the vacuum permeability, the first electrical conductivity, and the negative half power of the first resonant angular frequency, the transmitting device can be in the critical coupling state when the transmitting device transmits the electric energy to the receiving device, so that the transmission efficiency is obviously improved.

Example two

Fig. 2 is a flowchart of a wireless power transmission method according to another embodiment of the present invention, and as shown in fig. 2, the wireless power transmission method includes:

step 201, the transmitting device transmits energy corresponding to the acquired alternating current to a transmitting coil in the transmitting device through an exciting coil in the transmitting device. Wherein the wire diameter a of the transmitting coil₁The following formula is satisfied:

$D=\sqrt[3]{{\mathrm{\πa}}_1}\sqrt[6]{\frac{1}{2}{\mathrm{\μ}}_0{\mathrm{\ω}}_1{\mathrm{\σ}}_1}{r}_1;$

wherein D is a transmission distance, mu₀Is a vacuum magnetic permeability, omega₁At a first resonant angular frequency, σ₁Is a first conductivity, r₁Is the radius of the transmit coil.

From the above formula one can deduceI.e. the wire diameter of the transmitting coil is proportional to the cube of the transmission distance divided by the radius of the transmitting coil and proportional to the vacuum permeability, the first electrical conductivity of the transmitting coil, the minus half power of the first resonance angular frequency at which the transmitting coil operates, respectively.

In step 202, the transmitting device transmits electrical energy to the receiving device via the transmitting coil, the electrical energy being generated by the transmitting coil in accordance with the energy.

In order to facilitate understanding of the technical solution provided in this embodiment, an obtaining method of the above formula is provided below.

Specifically, for the transmitting device, the circuit of the exciting coil can be reflected to the transmitting coil, that is, an induced electromotive force is added to the transmitting coil. For the receiving device, the receiving device comprises a receiving coil and a load coil, and the load coil can be reflected to the receiving coil, namely, a reflection impedance is added to the receiving coil. Fig. 3 is an equivalent circuit diagram of a transmitting device and a receiving device according to an embodiment of the present invention, and the following formula can be obtained according to an analysis of the equivalent circuit diagram of fig. 3:

$\left\{\begin{array}{c}{\stackrel{\·}{U}}_S=(R_1+R_2+{\mathrm{j\ωL}}_2+\frac{1}{{\mathrm{j\ωC}}_2}){\stackrel{\·}{I}}_1-{\mathrm{j\ωM}}_{23}{\stackrel{\·}{I}}_2\\ 0=(R_3+R_4+{\mathrm{j\ωL}}_3+\frac{1}{{\mathrm{j\ωC}}_3}){\stackrel{\·}{I}}_2-{\mathrm{j\ωM}}_{23}{\stackrel{\·}{I}}_1\end{array}\right.;---\left(1\right)$

wherein, U_SThe exciting coil of the transmitting device is equivalent to the induced electromotive force of the transmitting coil,is U_SAmplitude vector of (2), R₁Is the sum of the internal resistance of the excitation source of the excitation coil and the impedance, R, of the first equivalent capacitance of the excitation coil to the transmitter coil₂The sum of the impedance of the second loss resistor and the impedance of the second radiation resistor of the transmitting coil and the impedance of the first loss resistor and the first radiation resistor of the exciting coil; m₂₃Is the mutual inductance between the transmitter coil and the receiver coil, R₃Is the sum of the third loss resistance and the third radiation resistance of the receiving coil and the fourth loss resistance and the fourth radiation resistance of the load coil, R₄Is the sum of the load coil of the receiving device and the impedance of the fourth equivalent capacitor equivalent to the receiving coil. L is₂A second inductance being a transmitting coil, L₃A third inductance of the receiving coil, C₂A second equivalent capacitance being a transmitting coil, C₃Is the third equivalent capacitance of the receive coil. j is an imaginary unit, I₁In order for the current to flow through the emitting device,is I₁Amplitude vector of (1)₂In order for the current to flow through the receiving means,is I₂ω is the angular frequency of the transmitting or receiving device, I₁And I₂Is clockwise in fig. 3.

Alternatively, the transmitting device and the receiving device can be designed to be of the same size and mechanical construction, in which case R is then present₁+R₂＝R₂+R₃，L₂＝L₃，C₂＝C₃Wherein, let R₁+R₂＝R₂+R₃＝R，L₂＝L₃＝L，C₂＝C₃＝C，M₂₃M, and introduces a generalized detuning factor ξ:

wherein, $\begin{array}{cc}\mathrm{\ξ}=Q(\frac{\mathrm{\ω}}{{\mathrm{\ω}}_0}-\frac{{\mathrm{\ω}}_0}{\mathrm{\ω}}),& Q=\frac{{\mathrm{\ω}}_{0}L}{R}=\frac{1}{{\mathrm{\ω}}_{0}CR}\end{array},$ q is a quality factor, omega₀For the resonant frequency, the following equation can be obtained according to equation (1):

${\stackrel{\·}{I}}_2=\frac{j\left(\frac{\mathrm{\ω}M}{R}\right){\stackrel{\·}{U}}_S\frac{1}{R}}{{(1+j\mathrm{\ξ})}^2+{\left(\frac{\mathrm{\ω}M}{R}\right)}^2};---\left(2\right)$

further, a coupling factor η is defined, wherein,then the voltage received by the receiving device can be obtained according to equation (2) as:

$\stackrel{\·}{U}={\stackrel{\·}{I}}_{2}R=\frac{j\left(\frac{\mathrm{\ω}M}{R}\right){\stackrel{\·}{U}}_S}{{(1+j\mathrm{\ξ})}^2+{\left(\frac{\mathrm{\ω}M}{R}\right)}^2}=\frac{j\mathrm{\η}{\stackrel{\·}{U}}_S}{{(1+j\mathrm{\ξ})}^2+{\mathrm{\η}}^2};---\left(3\right)$

wherein U is a receiving voltage of the electric energy received by the load of the receiving device,is a vector representation of U.

According to the receiving voltage U, the modulus of the receiving voltage is obtained as follows:

$\left|U\right|=\frac{{\mathrm{\ηU}}_S}{\sqrt{{(1-{\mathrm{\ξ}}^2+{\mathrm{\η}}^2)}^2+4{\mathrm{\ξ}}^2}};---\left(4\right)$

wherein | U | is the modulus of U.

Deriving the modulus value | U | of the received voltageCan be obtained at ξ₁0 andobtaining the extreme value of the module value of the received voltage_maxI is:

then, normalizing the received voltage of the electric energy received by the load of the receiving device, wherein the specific normalization method is to divide the extreme value of the received voltage module value by the received voltage module value to obtain a normalized voltage α:

$\mathrm{\α}=\frac{\left|U\right|}{\left|U_{max}\right|}=\frac{2\mathrm{\η}}{\sqrt{{(1+{\mathrm{\η}}^2)}^2+2(1-{\mathrm{\η}}^2){\mathrm{\ξ}}^2+{\mathrm{\ξ}}^4}};---\left(5\right)$

from the analysis of equation (5), it can be seen that when ξ is 0, i.e. when the transmitter operates at the resonant frequency ω₀The method comprises the following steps:

and is arranged atWhen the voltage received by the load of the receiving device is the maximum value;

at the position eta > 1, a frequency splitting phenomenon exists, namely, the phenomenon that two different resonant frequencies appear in the electric energy transmission process is the frequency splitting, but no matter which resonant frequency position, the load can still receive the maximum voltage value;

at η < 1, the voltage that the load can receive drops sharply as the coupling coefficient decreases.

Further, the mutual inductance M between the transmitting device and the receiving device is:

$M=M_{23}=\frac{{\mathrm{\&pi;\&mu;}}_0{\left(n_1{n}_2\right)}^{0.5}{\left(r_1{r}_2\right)}^2}{2D^3};---\left(6\right)$

wherein, mu₀In order to achieve a magnetic permeability in a vacuum,n₁number of turns of transmitting coil in transmitting device, n₂The number of turns of the receiving coil in the receiving device, r₁Radius of the transmitting coil, r₂The radius of the receiving coil, D, is the transmission distance. Since the transmit coil and the receive coil are of the same structural size, n₁＝n₂，r₁＝r₂Equation (6) is noted as:

$M=\frac{{\mathrm{\&pi;\&mu;}}_0{n}_1{r_1}^4}{2D^3};---\left(7\right)$

and, in general, the magnetic coupling resonance operating frequency is between 1 MHz and 50 MHz, and the loss resistance R of the transmitting coil is under the high frequency condition₀Comprises the following steps:

$R_0=\sqrt{\frac{{\mathrm{\&omega;\&mu;}}_0}{2{\mathrm{\&sigma;}}_1}}\&CenterDot;\frac{n_1{r}_1}{a_1};---\left(8\right)$

where ω is the angular frequency of the transmitting device, σ₁Is the electrical conductivity of the transmitter coil, i.e. the first electrical conductivity, a₁Is the wire diameter of the transmitting coil. When necessary, loss resistance R of the transmitting coil₀Is namely R₁And R₂The sum of (a) and (b).

When the transmitting means operate at resonance frequency, i.e.When the voltage received by the load of the receiving device is the maximum value, the formula (7) and the formula (8) are substituted intoCan obtain $D=\sqrt[3]{{\mathrm{\&pi;a}}_1}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_0{\mathrm{\&omega;}}_1{\mathrm{\&sigma;}}_1}{r}_1.$

Since the resonance frequency of the transmitting device is equal to the resonance frequency of the receiving device, i.e. ω ═ ω₁＝ω₂Wherein, ω is₁Is the resonant frequency of the transmitting device, denoted as the first resonant angular frequency, ω₂For resonance of receiving meansFrequency, denoted as second resonant angular frequency. Therefore, the temperature of the molten metal is controlled,

therefore, under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius and the resonant working frequency of the transmitting coil are fixed, if the line diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil and is in direct proportion to the vacuum permeability, the first electric conductivity and the negative half power of the first resonant angular frequency respectively, the transmitting device can be in a critical coupling state when the transmitting device transmits electric energy to the receiving device, and the transmission efficiency is obviously improved.

EXAMPLE III

Fig. 4 is a flowchart of a wireless power transmission method according to another embodiment of the present invention, where an execution main body of the wireless power transmission method provided in this embodiment is a receiving device, and as shown in fig. 4, the wireless power transmission method includes:

step 301, the receiving device receives the electric energy transmitted by the transmitting device through a receiving coil of the receiving device.

And step 302, the receiving device transmits the electric energy to a load coil in the receiving device through the receiving coil, wherein the wire diameter of the receiving coil is proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is respectively proportional to the vacuum magnetic permeability, the second electric conductivity of the receiving coil and the negative half power of the second resonance angular frequency of the work of the receiving coil, and the distance between the transmitting device and the receiving device is the transmission distance.

The second conductivity is determined by the material of the receiving coil, the receiving coil may be a copper wire or an aluminum wire, the transmission distance and the coil radius of the transmitting coil may be selected according to actual needs, for example, the transmission distance may be selected to be 50 cm, and in order to limit the volume of the receiving device, the radius of the receiving coil may be selected to be 10 cm.

It can be seen that, when the transmission distance D between the receiving device and the transmitting device is fixed, and the material, the coil radius, and the resonant operating frequency of the receiving coil of the receiving device are fixed, if the line diameter of the receiving coil is directly proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is directly proportional to the vacuum permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency, respectively, the receiving device is in the critical coupling state when the receiving device receives the electric energy transmitted by the transmitting device, so that the transmission efficiency is significantly improved.

Example four

Fig. 5 is a flowchart of a wireless power transmission method according to still another embodiment of the present invention, as shown in fig. 5, the wireless power transmission method includes:

step 401, the receiving device receives the electric energy transmitted by the transmitting device through a receiving coil of the receiving device.

Step 402, the receiving device transmits the electric energy to a load coil in the receiving device through the receiving coil.

Wherein the wire diameter a of the receiving coil₂The following formula is satisfied:

wherein D is a transmission distance, a₂Is the wire diameter of the receiving coil, mu₀Is a vacuum magnetic permeability, omega₂At a second resonance angular frequency, σ₂Is a second conductivity, r₂Is the radius of the receive coil.

From the above formula one can deduce

In order to facilitate understanding of the technical solution provided in this embodiment, an obtaining method of the above formula is provided below.

Specifically, for the receiving device, the receiving device comprises a receiving coil and a load coil, and the load coil can be reflected to the receiving coil, namely, a reflection impedance is added to the receiving coil. For the transmitting device, the circuit of the exciting coil can be reflected to the transmitting coil, namely, the circuit is equivalent to adding an induced electromotive force to the transmitting coil. Similarly, as shown in FIG. 3, from the analysis of the simplified circuit diagram of FIG. 3, the following formula can be obtained:

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_S=(R_1+R_2+{\mathrm{j\&omega;L}}_2+\frac{1}{{\mathrm{j\&omega;C}}_2}){\stackrel{\&CenterDot;}{I}}_1-{\mathrm{j\&omega;M}}_{23}{\stackrel{\&CenterDot;}{I}}_2\\ 0=(R_3+R_4+{\mathrm{j\&omega;L}}_3+\frac{1}{{\mathrm{j\&omega;C}}_3}){\stackrel{\&CenterDot;}{I}}_2-{\mathrm{j\&omega;M}}_{23}{\stackrel{\&CenterDot;}{I}}_1\end{array}\right.;---\left(1\right)$

U_Sthe exciting coil of the transmitting device is equivalent to the induced electromotive force of the transmitting coil,is U_SAmplitude vector of (2), R₁Is the sum of the internal resistance of the excitation source of the excitation coil and the impedance, R, of the first equivalent capacitance of the excitation coil to the transmitter coil₂The sum of the impedance of the second loss resistor and the impedance of the second radiation resistor of the transmitting coil and the impedance of the first loss resistor and the first radiation resistor of the exciting coil; m₂₃Is the mutual inductance between the transmitter coil and the receiver coil, R₃Is the sum of the third loss resistance and the third radiation resistance of the receiving coil and the fourth loss resistance and the fourth radiation resistance of the load coil, R₄Is the sum of the load coil of the receiving device and the impedance of the fourth equivalent capacitor equivalent to the receiving coil. L is₂A second inductance being a transmitting coil, L₃A third inductance of the receiving coil, C₂A second equivalent capacitance being a transmitting coil, C₃Is the third equivalent capacitance of the receive coil. j is an imaginary unit, I₁In order for the current to flow through the emitting device,is I₁Amplitude vector of (1)₂In order for the current to flow through the receiving means,is I₂ω is the angular frequency of the transmitting or receiving device, I₁And I₂Is clockwise in fig. 3.

Alternatively, the transmitting device and the receiving device can be designed to be of the same size and mechanical construction, in which case R is then present₁+R₂＝R₂+R₃，L₂＝L₃，C₂＝C₃Wherein, let R₁+R₂＝R₂+R₃＝R，L₂＝L₃＝L，C₂＝C₃＝C，M₂₃Is equal to M, andand introduces a generalized detuning factor ξ:

wherein, $\begin{array}{cc}\mathrm{\&xi;}=Q(\frac{\mathrm{\&omega;}}{{\mathrm{\&omega;}}_0}-\frac{{\mathrm{\&omega;}}_0}{\mathrm{\&omega;}}),& Q=\frac{{\mathrm{\&omega;}}_{0}L}{R}=\frac{1}{{\mathrm{\&omega;}}_{0}CR}\end{array},$ q is a quality factor, omega₀For the resonant frequency, the following equation can be obtained according to equation (1):

${\stackrel{\&CenterDot;}{I}}_2=\frac{j\left(\frac{\mathrm{\&omega;}M}{R}\right){\stackrel{\&CenterDot;}{U}}_S\frac{1}{R}}{{(1+j\mathrm{\&xi;})}^2+{\left(\frac{\mathrm{\&omega;}M}{R}\right)}^2};---\left(2\right)$

further, a coupling factor η is defined, wherein,then the voltage received by the receiving device can be obtained according to equation (2) as:

$\stackrel{\&CenterDot;}{U}={\stackrel{\&CenterDot;}{I}}_{2}R=\frac{j\left(\frac{\mathrm{\&omega;}M}{R}\right){\stackrel{\&CenterDot;}{U}}_S}{{(1+j\mathrm{\&xi;})}^2+{\left(\frac{\mathrm{\&omega;}M}{R}\right)}^2}=\frac{j\mathrm{\&eta;}{\stackrel{\&CenterDot;}{U}}_S}{{(1+j\mathrm{\&xi;})}^2+{\mathrm{\&eta;}}^2};---\left(3\right)$

wherein U is a receiving voltage of the electric energy received by the load of the receiving device,is a vector representation of U.

According to the receiving voltage U, the modulus of the receiving voltage is obtained as follows:

$\left|U\right|=\frac{{\mathrm{\&eta;U}}_S}{\sqrt{{(1-{\mathrm{\&xi;}}^2+{\mathrm{\&eta;}}^2)}^2+4{\mathrm{\&xi;}}^2}};---\left(4\right)$

wherein | U | is the modulus of U.

Deriving the modulus value | U | of the received voltageCan be obtained at ξ₁0 andobtaining the extreme value of the module value of the received voltage_maxI is:

then, the received voltage of the electric energy received by the load of the receiving device is normalized, and the specific normalization method is that the extreme value of the received voltage modulus is divided by the received voltage modulus, so that the normalized voltage α is obtained as:

$\mathrm{\&alpha;}=\frac{\left|U\right|}{\left|U_{max}\right|}=\frac{2\mathrm{\&eta;}}{\sqrt{{(1+{\mathrm{\&eta;}}^2)}^2+2(1-{\mathrm{\&eta;}}^2){\mathrm{\&xi;}}^2+{\mathrm{\&xi;}}^4}};---\left(5\right)$

from the analysis of equation (5), it can be seen that ξ is 0, i.e., when the transmitter is operating at the resonant frequency ω₀The method comprises the following steps:

and is arranged atWhen the voltage received by the load of the receiving device is the maximum value;

at the position eta > 1, a frequency splitting phenomenon exists, namely, the phenomenon that two different resonant frequencies appear in the electric energy transmission process is the frequency splitting, but no matter which resonant frequency position, the load can still receive the maximum voltage value;

at η < 1, the voltage that the load can receive drops sharply as the coupling coefficient decreases.

Further, the mutual inductance M between the transmitting device and the receiving device is:

$M=M_{23}=\frac{{\mathrm{\&pi;\&mu;}}_0{\left(n_1{n}_2\right)}^{0.5}{\left(r_1{r}_2\right)}^2}{2D^3};---\left(6\right)$

wherein, mu₀Is a vacuum permeability, n₁Number of turns of transmitting coil in transmitting device, n₂The number of turns of the receiving coil in the receiving device, r₁Radius of the transmitting coil, r₂The radius of the receiving coil, D, is the transmission distance. Due to the transmitting coilThe same size as the structure of the receiving coil, therefore, n₁＝n₂，r₁＝r₂Equation (6) is noted as:

$M=\frac{{\mathrm{\&pi;\&mu;}}_0{n}_2{r_2}^4}{2D^3};---\left(7^{*}\right)$

and, generally, the magnetic coupling resonance operating frequency is between 1 MHz and 50 MHz, and the loss resistance R of the receiving coil is under the high frequency condition₀' is:

${R_0}^{\&prime;}=\sqrt{\frac{{\mathrm{\&omega;\&mu;}}_0}{2{\mathrm{\&sigma;}}_2}}\&CenterDot;\frac{n_2{r}_2}{a_2};---\left(8^{*}\right)$

where ω is the angular frequency of the receiving device, σ₂Is the electrical conductivity of the transmitter coil, i.e. the second electrical conductivity, a₂Is the wire diameter of the receiving coil. The loss resistance R of the receiver coil₀' is R₃And R₄The sum of (a) and (b).

When the receiving means operate at resonance frequency, i.e.When the voltage received by the load of the receiving device is the maximum value, the formula (7)^*) And formula (8)^*) Substitution intoCan obtain $D=\sqrt[3]{{\mathrm{\&pi;a}}_2}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_0{\mathrm{\&omega;\&sigma;}}_2}{r}_2.$

Since the resonance frequency of the receiving means is equal to the resonance frequency of the transmitting means, i.e. ω ═ ω₁＝ω₂Wherein, ω is₂Is the resonance frequency of the receiving device, denoted as the second resonance angular frequency, ω₁Is the resonant frequency of the transmitting device, noted as the first resonant angular frequency. Therefore, the temperature of the molten metal is controlled,

it can be seen that, under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius, and the resonant operating frequency of the receiving coil are fixed, if the line diameter of the receiving coil is directly proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is respectively directly proportional to the vacuum permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency, the receiving device is in the critical coupling state when the receiving device receives the electric energy transmitted by the transmitting device, so that the transmission efficiency is obviously improved.

EXAMPLE five

In this embodiment, a wireless power transmitting apparatus is provided for performing the wireless power transmission method of the first embodiment and the second embodiment, and fig. 6 is a circuit diagram of the wireless power transmitting apparatus provided in this embodiment, as shown in fig. 6, the wireless power transmitting apparatus includes: an exciting coil 11 for transmitting energy corresponding to the acquired alternating current to the transmitting coil, and a transmitting coil 12 for transmitting electric energy generated according to the above energy to the wireless power receiving apparatus.

Wherein the wire diameter of the transmitting coil 12 is proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is respectively proportional to the vacuum permeability, the first electrical conductivity of the transmitting coil, and the minus half power of the first resonance angular frequency at which the transmitting coil operates; the distance between the transmitting device and the receiving device is a transmission distance.

The excitation coil 11 includes an excitation source and a single-turn coil connected in series, and the transmitting coil 12 is a multi-turn coil. The number of coil turns of the transmitter coil 12 may be determined based on the resonant frequency at which the transmitter device operates.

Under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius and the resonant working frequency of the transmitting coil 12 are fixed, if the wire diameter of the transmitting coil 12 is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil 12 and is in direct proportion to the vacuum permeability, the first electrical conductivity and the negative half power of the first resonant angular frequency respectively, the transmitting device can be in a critical coupling state when the transmitting device transmits electric energy to the receiving device, and the transmission efficiency is obviously improved.

EXAMPLE six

This embodiment is a further supplementary explanation of the above embodiment, in which the wire diameter a of the transmitting coil 12₁The following formula is satisfied:

$D=\sqrt[3]{{\mathrm{\&pi;a}}_1}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_{0_1}{\mathrm{\&omega;}}_1{\mathrm{\&sigma;}}_1}{r}_1;$

wherein D is a transmission distance, a₁Is the wire diameter of the transmitting coil, mu₀Is a vacuum magnetic permeability, omega₁At a first resonant angular frequency, σ₁Is a first conductivity, r₁Is the radius of the transmit coil.

Further, an equivalent circuit of the exciting coil 11 can be obtained by making an internal resistance, a capacitance, and the like of the exciting coil 11 equivalent, and as shown in fig. 6, the equivalent circuit includes: first radiation resistors R connected in series_rad1And excitationThe first loss resistance R of the coil 11 due to skin effect and the like_p1Internal resistance R of the excitation source_sA first equivalent capacitor C₁A first inductor L₁。

Similarly, the transmitting coil 12 may also obtain an equivalent circuit, as shown in fig. 6, the equivalent circuit of the transmitting coil 12 includes: second radiation resistors R connected in series_rad2Second loss resistance R generated by the transmitting coil 12 due to skin effect and the like_p2A second equivalent capacitor C₂And a second inductance L₂。

Further, the equivalent circuit of the exciting coil 11 can be reflected to the transmitting coil 12 to obtain the equivalent circuit of the transmitting device, as shown in fig. 3, wherein the equivalent circuit of the transmitting device comprises the internal resistance R of the excitation source of the exciting coil 11_sAnd a first equivalent capacitance C of the excitation coil 11₁Sum of impedances R equivalent to the transmitting coil 12₁First loss resistance R of the field coil 11_p1And a first radiation resistor R_rad1And a second loss resistance R of the transmitter coil 12_p2And a second radiation resistor R_rad2Sum of impedances R equivalent to the transmitting coil 12₂A second inductance L of the transmitter coil 12₂A second equivalent capacitance C of the transmitting coil 12₂。

Specifically, the method for obtaining the wire diameter of the transmitting coil 12 can refer to the detailed description of the second embodiment, and is not repeated herein.

Under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius and the resonant working frequency of the transmitting coil 11 are fixed, if the wire diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil and is in direct proportion to the vacuum magnetic permeability, the first electric conductivity and the negative half power of the first resonant angular frequency respectively, the transmitting device can be in a critical coupling state when the transmitting device transmits electric energy to the receiving device, so that the transmission efficiency is obviously improved.

EXAMPLE seven

The present embodiment provides a radio energy receiving apparatus for performing the radio energy transmission methods of the third embodiment and the fourth embodiment, and fig. 7 is a circuit schematic diagram of the radio energy receiving apparatus provided in the present embodiment, as shown in fig. 7, the radio energy receiving apparatus includes: a receiving coil 21 for receiving the power transmitted by the transmitting device, and a loading coil 22 for receiving the power transmitted by the receiving coil 21.

Specifically, the receiving coil 21 is a multi-turn coil, and the load coil 22 includes a load and a single-turn coil connected in series.

The wire diameter of the receiving coil 21 is proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is proportional to the second vacuum magnetic permeability, the second electrical conductivity, and the negative half power of the second resonance angular frequency, respectively, and the distance between the transmitting device and the receiving device is the transmission distance.

Specifically, the receiving coil 21 is a multi-turn coil, and the load coil 22 includes a load and a single-turn coil connected in series.

The second conductivity is determined by the material of the receiving coil 21, the receiving coil 21 may be a copper wire or an aluminum wire, the transmission distance and the radius of the receiving coil 21 may be selected according to actual needs, for example, the transmission distance may be selected to be 50 cm, and in order to limit the volume of the receiving device, the radius of the receiving coil 21 may be selected to be 10 cm.

It can be seen that, when the transmission distance D between the receiving device and the transmitting device is fixed, and the material, the coil radius, and the resonant operating frequency of the receiving coil 21 of the receiving device are fixed, and the wire diameter of the receiving coil 21 is directly proportional to the cube of the transmission distance divided by the radius of the receiving coil 21, and is directly proportional to the vacuum permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency, respectively, the receiving device is in the critical coupling state when the receiving device receives the electric energy transmitted by the transmitting device, so that the transmission efficiency is significantly improved.

Example eight

The present embodiment is a further explanation of the above-described embodiment in which the wire diameter a of the receiving coil 21₂The following formula is satisfied:

$D=\sqrt[3]{{\mathrm{\&pi;a}}_2}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_0{\mathrm{\&omega;}}_2{\mathrm{\&sigma;}}_2}{r}_2;$

wherein D is a transmission distance, a₂Is the wire diameter of the receiving coil, mu₀Is a vacuum magnetic permeability, omega₂At a second resonance angular frequency, σ₂Is a second conductivity, r₂Is the radius of the receive coil.

Further, an equivalent circuit of the reception coil 21 can be obtained by making an equivalent of the internal resistance, capacitance, and the like of the reception coil 21, and as shown in fig. 7, the equivalent circuit includes: third radiation resistors R connected in series_rad3And a third loss resistance R of the receiving coil 21 due to skin effect and the like_p3A third equivalent capacitor C₃A third inductor L₃。

Similarly, the load coil 22 may also obtain an equivalent circuit, as shown in fig. 7, the equivalent circuit of the load coil 22 includes: fourth radiation resistors R connected in series_rad4And a fourth loss resistance R of the load coil 22 due to skin effect and the like_p4A fourth inductor L₄A fourth equivalent capacitor C₄And a load R_L。

Further, the equivalent circuit of the load coil 22 may be reflected to the receiving coil 21 to obtain an equivalent circuit of the receiving apparatus, as shown in fig. 3, where the equivalent circuit of the receiving apparatus includes: third radiation resistance R of the receiving coil 21_rad3And a third loss resistance R_p3And a fourth radiation resistance R of the load coil 22_rad4And the sum R of the impedances of the fourth loss resistor Rp4₃Load R of load coil 22_LAnd a fourth capacitance C₄Sum R of impedances equivalent to the receiving coil 21₄A third equivalent capacitance C of the receiving coil 21₃A third inductance L of the receiving coil 21₃。

Specifically, the method for obtaining the wire diameter of the receiving coil 21 can refer to the detailed description of the fourth embodiment, and is not repeated herein.

Under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius and the resonant working frequency of the receiving coil are fixed, if the line diameter of the receiving coil is in direct proportion to the cube of the transmission distance divided by the radius of the receiving coil and is in direct proportion to the vacuum magnetic permeability, the second electric conductivity and the negative half power of the second resonance angular frequency respectively, the receiving device can be in a critical coupling state when the receiving device receives the electric energy transmitted by the transmitting device, so that the transmission efficiency is obviously improved.

Example nine

The present embodiment provides a power transmission system, as shown in fig. 3, which includes the power transmitting device 1 and the wireless power receiving device 2 provided in the above embodiments, wherein the wire diameter of the transmitting coil and the wire diameter of the receiving coil are equal, the first resonance angular frequency and the second resonance angular frequency are equal, the first conductivity and the second conductivity are equal, and the radius of the transmitting coil and the radius of the receiving coil are equal. I.e. the transmitting means and the receiving means can be designed with the same dimensions and mechanical structure. And, the transmitting coil and the receiving coil are helical coils and are coaxially disposed.

It can be seen that, under the condition that the transmission distance D between the transmitting device and the receiving device is fixed, and the material, the coil radius, and the resonant operating frequency of the receiving coil are fixed, if the line diameter of the receiving coil is directly proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is respectively directly proportional to the vacuum magnetic permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency, when the receiving device receives the electric energy transmitted by the transmitting device, the whole electric energy transmission system is in a critical coupling state, so that the transmission efficiency is obviously improved.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A wireless power transmission method, comprising:

the transmitting device transmits the energy corresponding to the acquired alternating current to a transmitting coil in the transmitting device through an exciting coil in the transmitting device;

the transmitting device transmits electric energy to the receiving device through the transmitting coil, and the electric energy is generated by the transmitting coil according to the energy;

the wire diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil, and is in direct proportion to the vacuum magnetic permeability, the first electric conductivity of the transmitting coil and the negative half power of the first resonance angular frequency of the work of the transmitting coil respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

2. The wireless power transmission method according to claim 2, wherein a wire diameter a of the transmitting coil₁The following formula is satisfied:

$D=\sqrt[3]{{\mathrm{\&pi;a}}_1}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_0{\mathrm{\&omega;}}_1{\mathrm{\&sigma;}}_1}{r}_1;$

wherein D is a transmission distance, mu₀Is a vacuum magnetic permeability, omega₁At a first resonant angular frequency, σ₁Is a first conductivity, r₁Is the radius of the transmit coil.

3. A wireless power transmission method, comprising:

the receiving device receives the electric energy transmitted by the transmitting device through a receiving coil of the receiving device;

the receiving device transmits the electric energy to a load coil in the receiving device through the receiving coil;

the wire diameter of the receiving coil is in direct proportion to the cube of the transmission distance divided by the radius of the receiving coil, and is in direct proportion to the vacuum magnetic permeability, the second electric conductivity of the receiving coil and the negative half power of the second resonance angular frequency of the work of the receiving coil respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

4. The wireless power transmission method according to claim 3, wherein a wire diameter a of the receiving coil₂The following formula is satisfied:

$D=\sqrt[3]{{\mathrm{\&pi;a}}_2}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_{0_2}{\mathrm{\&omega;}}_2{\mathrm{\&sigma;}}_2}{r}_2;$

wherein D is a transmission distance, a₂Which is the wire diameter of the receiving coil,is the second vacuum permeability, ω₂At a second resonance angular frequency, σ₂Is a second conductivity, r₂Is the radius of the receive coil.

5. A wireless power transmitting device, comprising: an excitation coil for transmitting energy corresponding to the acquired alternating current to a transmitting coil, and the transmitting coil for transmitting electric energy generated according to the energy to a wireless electric energy receiving device;

the wire diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil, and is in direct proportion to the vacuum magnetic permeability, the first electric conductivity of the transmitting coil and the negative half power of the first resonance angular frequency of the work of the transmitting coil respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

6. The apparatus of claim 5, wherein the excitation coil comprises an excitation source and a single turn coil connected in series, and the transmission coil is a multi-turn coil.

7. The wireless power transmission apparatus of claim 5, wherein the wire diameter a of the transmission coil₁The following formula is satisfied:

$D=\sqrt[3]{{\mathrm{\&pi;a}}_1}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_0{\mathrm{\&omega;}}_1{\mathrm{\&sigma;}}_1}{r}_1;$

wherein D is a transmission distance, a₁Is the wire diameter of the transmitting coil, mu₀Is a vacuum magnetic permeability, omega₁At a first resonant angular frequency, σ₁Is a first conductivity, r₁Is the radius of the transmit coil.

8. A wireless power receiving device, comprising:

the receiving coil is used for receiving the electric energy transmitted by the transmitting device, and the load coil is used for receiving the electric energy transmitted by the receiving coil;

wherein the wire diameter of the receiving coil is proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is proportional to the second vacuum permeability, the second electrical conductivity, and the negative half power of the second resonance angular frequency, respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

9. The device of claim 8, wherein the wire diameter a of the receiving coil is larger than the wire diameter of the receiving coil₂The following formula is satisfied:

$D=\sqrt[3]{{\mathrm{\&pi;a}}_2}\sqrt[6]{\frac{1}{2}{\mathrm{\&mu;}}_{0_2}{\mathrm{\&omega;}}_2{\mathrm{\&sigma;}}_2}{r}_2;$

wherein D is a transmission distance, a₂Is the wire diameter of the receiving coil, mu₀Is the second vacuum permeability, ω₂At a second resonance angular frequency, σ₂Is a second conductivity, r₂Is the radius of the receive coil.

10. A wireless power transfer system comprising any one of the wireless power transmitting apparatus of claims 5 to 7 and any one of the wireless power receiving apparatus of claims 8 to 9, wherein the wire diameter of the transmitting coil is equal to the wire diameter of the receiving coil, the first resonance angular frequency is equal to the second resonance angular frequency, the first conductivity is equal to the second conductivity, and the radius of the transmitting coil is equal to the radius of the receiving coil.